Difference between revisions of "Attribute Conventions for Data Discovery 2.0"

From Earth Science Information Partners (ESIP)
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==Recommended==
=Recommended= <table width="95%" border="1" cellpadding="2" cellspacing="2">
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<!--<table width="95%" border="1" cellpadding="2" cellspacing="2">
 
             <tr>
 
             <tr>
 
                 <th valign="top">Attribute</th>
 
                 <th valign="top">Attribute</th>
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                 <th valign="top">Rubric Category</th>
 
                 <th valign="top">Rubric Category</th>
 
             </tr>
 
             </tr>
            <!--
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</table>
            ; id : ; naming_authority : ; cdm_data_type : ; history : ; source :  ; comment :
 
           
 
; date_content_modified : The date on which any of the provided content, including data, metadata, and presented format, was last created or changed (ISO 8601 format)
 
 
 
; date_values_modified: The date on which the provided data values were last created or changed; excludes metadata and formatting changes (ISO 8601 format)
 
 
 
; creator  : The name of the person principally responsible for originating this data.
 
; creator_email : The email address of the person principally responsible for originating this data.
 
; publisher : The person responsible for the data file or product, with its current metadata and format.
 
; publisher_email : The email address of the person responsible for the data file or product.
 
; processing_level : A textual description of the processing (or quality control) level of the data.
 
; acknowledgement : A place to acknowledge various type of support for the project that produced this data.
 
; geospatial_bounds : Describes geospatial extent using any of the geometric objects (2D or 3D) supported by the Well-Known Text (WKT) format.
 
; geospatial_lat_min : Describes a simple lower latitude limit; may be part of a bounding box or cube. Geospatial_lat_min specifies the southernmost latitude covered by the dataset.
 
; geospatial_lat_max : Describes a simple upper latitude limit; may be part of a bounding box or cube. Geospatial_lat_max specifies the northernmost latitude covered by the dataset.
 
; geospatial_lon_min : Describes a simple longitude limit; may be part of a bounding box or cube. Geospatial_lon_min specifies the westernmost longitude covered by the dataset. Cases where geospatial_lon_min is greater than geospatial_lon_max indicate the bounding box extends from geospatial_lon_max, through the longitude range discontinuity meridian (either the antimeridian for -180:180 values, or Prime Meridian for 0:360 values), to geospatial_lon_min.
 
; geospatial_lon_max : Describes a simple longitude limit; may be part of a bounding box or cube. Geospatial_lon_max specifies the easternmost longitude covered by the dataset. Cases where geospatial_lon_min is greater than geospatial_lon_max indicate the bounding box extends from geospatial_lon_max, through the longitude range discontinuity meridian (either the antimeridian for -180:180 values, or Prime Meridian for 0:360 values), to geospatial_lon_min.
 
; geospatial_vertical_min : Describes a numerically smaller vertical limit; may be part of a bounding box or cube. If geospatial_vertical_positive is up ('altitude' orientation), the geospatial_vertical_min attribute specifies the location closest to the earth's center covered by the dataset. If geospatial_vertical_positive is down ('depth' orientation), the geospatial_vertical_min attribute specifies the location furthest from the earth's center covered by the dataset.
 
; geospatial_vertical_max : Describes a numerically larger vertical limit; may be part of a bounding box or cube. If geospatial_vertical_positive is up ('altitude' orientation), the geospatial_vertical_min attribute specifies the location furthest from  the earth's center covered by the dataset. If geospatial_vertical_positive is down ('depth' orientation), the geospatial_vertical_min attribute specifies the location closest to the earth's center covered by the dataset.
 
; geospatial_vertical_positive : One of 'up' or 'down'. If up, vertical values are interpreted as 'altitude', with negative values corresponding to below the reference datum (e.g., under water). If down, vertical values are interpreted as 'depth', positive values correspond to below the reference datum.
 
; time_coverage_start : Describes the time of the first data point in the data set. ISO8601 format recommended.
 
; time_coverage_end : Describes the time of the last data point in the data set. ISO8601 format recommended.
 
; time_coverage_duration : Describes the duration of the data set. ISO8601 duration format recommended.
 
; time_coverage_resolution : Describes the targeted time period between each value in the data set. ISO8601 duration format recommended.
 
; license : Provide the URL to a standard or specific license, enter "Freely Distributed" or "None", or describe any restrictions to data access and distribution in free text.
 
 
 
            -->
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#id_Attribute id] </td>
 
                <td rowspan="2" colspan="1" valign="top">An identifier for the data set, provided by and unique within its naming authority. The combination of the "naming authority" and the "id" should be globally unique, but the id can be globally unique by itself also. IDs can be URLs, URNs, DOIs, meaningful text strings, a local key, or any other unique string of characters. The id should not include blanks.</td>
 
                <td rowspan="2" valign="top">dataset@id </td>
 
                <td rowspan="2" colspan="1" valign="top">/gmi:MI_Metadata/gmd:fileIdentifier/gco:CharacterString (O) </td>
 
                <td rowspan="2">Identifier</td>
 
                <td rowspan="2">Identifier</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#naming_authority_Attribute naming_authority] </td>
 
                <td valign="top">The organization that provides the initial id (see above) for the dataset. The naming authority should be uniquely specified by this attribute.</td>
 
                <td></td>
 
                <td></td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#keywords_vocabulary_Attribute keywords_vocabulary] </td>
 
                <td valign="top">If you are following a guideline for the words/phrases in your "keywords" attribute, put the name of that guideline here. </td>
 
                <td valign="top">metadata/keyword@vocabulary</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:thesaurusName/gmd:CI_Citation/gmd:title/gco:CharacterString </td>
 
                <td></td>
 
                <td>Text Search</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#cdm_data_type_Attribute cdm_data_type] </td>
 
                <td>The organization of the data, as derived from the Common Data Model's Scientific Data layer and understood by THREDDS (this is a [http://www.unidata.ucar.edu/projects/THREDDS/tech/catalog/InvCatalogSpec.html#dataType THREDDS "dataType"]). One of point, profile, section, station, station_profile, trajectory, grid, image, or swath. Please note that this is different from the  CF NetCDF attribute 'featureType' that indicates a Discrete Sampling Geometry file - for guidance on those terms, please see  [http://www.nodc.noaa.gov/data/formats/netcdf/ this NODC guidance].</td>
 
                <td valign="top">metadata/dataType</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:spatialRepresentationType/gmd:MD_SpatialRepresentationTypeCode May need some extensions to this codelist. Current values: vector, grid, textTable, tin, stereoModel, video. </td>
 
                <td></td>
 
                <td>Other</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#history_Attribute history]</td>
 
                <td valign="top">Describes the processes/transformations used to create this data; can serve as an audit trail. This attribute is defined in the [http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html#Attribute-Conventions NUG]: 'This is a character array with a line for each invocation of a program that has modified the dataset. Well-behaved generic netCDF applications should append a line containing: date, time of day, user name, program name and command arguments.'  To include a more complete description you can append an ISO Lineage reference; see [https://geo-ide.noaa.gov/wiki/index.php?title=ISO_Lineage NOAA EDM ISO Lineage guidance]. </td>
 
                <td valign="top">metadata/documentation[@type="history"]</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:dataQualityInfo/gmd:DQ_DataQuality/gmd:lineage/gmd:LI_Lineage/gmd:statement/gco:CharacterString (O)</td>
 
                <td></td>
 
                <td>Text Search</td>
 
            </tr>
 
        <tr>
 
            <td valign="top">source</td>
 
            <td valign="top">The method of production of the original data. If it was model-generated, source should name the model and its version. If it is observational, source should characterize it. This attribute is [http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#description-of-file-contents defined in CF].</td>
 
            <td valign="top"></td>
 
            <td valign="top"></td>
 
            <td></td>
 
            <td></td>
 
        </tr>
 
       
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#comment_Attribute comment] </td>
 
                <td valign="top"> Miscellaneous information about the data, not captured elsewhere.  This attribute is [http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#description-of-file-contents defined in CF].</td>
 
                <td valign="top">metadata/documentation </td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:supplementalInformation </td>
 
                <td></td>
 
                <td>Text Search</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#date_created_Attribute date_created]</td>
 
                <td valign="top">The date on which the data was created. </td>
 
                <td valign="top">metadata/date[@type="created"]</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:date/gmd:CI_Date/gmd:date/gco:Date (M) /gmd:dateType/gmd:CI_DateTypeCode="creation"</td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#creator_name_Attribute creator_name] </td>
 
                <td rowspan="4" colspan="1" valign="top">The data creator's name, URL, and email. The "institution" attribute will be used if the "creator_name" attribute does not exist. </td>
 
                <td valign="top">metadata/creator/name</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:citedResponsibleParty/gmd:CI_ResponsibleParty/gmd:individualName/gco:CharacterString CI_RoleCode="originator" (O)</td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#creator_url_Attribute creator_url] </td>
 
                <td valign="top">metadata/creator/contact@url</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:citedResponsibleParty/gmd:CI_ResponsibleParty/gmd:contactInfo/gmd:CI_Contact/gmd:onlineResource/gmd:CI_OnlineResource/gmd:linkage/gmd:URL</td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#creator_email_Attribute creator_email] </td>
 
 
 
                <td valign="top">metadata/creator/contact@email</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:citedResponsibleParty/gmd:CI_ResponsibleParty/gmd:contactInfo/gmd:CI_Contact/gmd:address/gmd:CI_Address/gmd:electronicMailAddress/gco:CharacterString</td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#institution_Attribute institution] </td>
 
                <td valign="top">metadata/creator/name</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:citedResponsibleParty/gmd:CI_ResponsibleParty/gmd:organisationName/gco:CharacterString</td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#project_Attribute project] </td>
 
                <td valign="top">The scientific project that produced the data. </td>
 
                <td valign="top">metadata/project</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gco:CharacterString<br />and/or<br />/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:aggregationInfo/gmd:MD_AggregateInformation/gmd:aggregateDataSetName/gmd:CI_Citation/gmd:title/gco:CharacterStringDS_AssociationTypeCode="largerWorkCitation" and DS_InitiativeTypeCode="project"<br />and/or<br /> /gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gco:CharacterString with gmd:MD_KeywordTypeCode="project" </td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
 
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#processing_level_Attribute processing_level]</td>
 
                <td valign="top">A textual description of the processing (or quality control) level of the data. </td>
 
                <td valign="top">metadata/documentation[@type="processing_level"]</td>
 
                <td></td>
 
                <td></td>
 
                <td></td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#acknowledgement_Attribute acknowledgement]</td>
 
                <td valign="top">A place to acknowledge various type of support for the project that produced this data. </td>
 
                <td valign="top">metadata/documentation[@type="funding"]</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:credit/gco:CharacterString</td>
 
                <td></td>
 
                <td>Responsible Party</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">geospatial_bounds</td>
 
                <td>Describes geospatial extent using any of the geometric objects (2D or 3D) supported by the [http://en.wikipedia.org/wiki/Well-known_text Well-Known Text] (WKT) format.</td>
 
                <td></td>
 
                <td></td>
 
                <td>BoundingPolygon</td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#geospatial_lat_min_Attribute geospatial_lat_min] </td>
 
                <td rowspan="4" colspan="1" valign="top">Describes a simple latitude/longitude bounding box. geospatial_lat_min specifies the southernmost latitude; geospatial_lat_max specifies the northernmost latitude; geospatial_lon_min specifies the westernmost longitude; geospatial_lon_max specifies the easternmost longitude of the bounding box.<br />The values of geospatial_lon_min and geospatial_lon_max reflect the actual longitude data values. Cases where geospatial_lon_min is greater than geospatial_lon_max indicate the bounding box extends from geospatial_lon_max, through the longitude range discontinuity meridian (either the antimeridian or Prime Meridian), to geospatial_lon_min.<br />For a more detailed geospatial coverage, see the [http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#suggested_geospatial suggested geospatial attributes]. </td>
 
                <td valign="top">metadata/geospatialCoverage/northsouth/start </td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:geographicElement/gmd:EX_GeographicBoundingBox/gmd:southBoundLatitude/gco:Decimal </td>
 
                <td>BoundingBox</td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#geospatial_lat_max_Attribute geospatial_lat_max]</td>
 
 
 
                <td valign="top">metadata/geospatialCoverage/northsouth/size</td>
 
 
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:geographicElement/gmd:EX_GeographicBoundingBox/gmd:northBoundLatitude/gco:Decimal </td>
 
                <td>BoundingBox</td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#geospatial_lon_min_Attribute geospatial_lon_min]</td>
 
 
 
                <td valign="top">metadata/geospatialCoverage/eastwest/start</td>
 
 
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:geographicElement/gmd:EX_GeographicBoundingBox/gmd:westBoundLongitude/gco:Decimal </td>
 
                <td>BoundingBox</td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#geospatial_lon_max_Attribute geospatial_lon_max]</td>
 
 
 
                <td valign="top">metadata/geospatialCoverage/eastwest/size</td>
 
 
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:geographicElement/gmd:EX_GeographicBoundingBox/gmd:eastBoundLongitude/gco:Decimal </td>
 
                <td>BoundingBox</td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#geospatial_vertical_min_Attribute geospatial_vertical_min] </td>
 
                <td rowspan="2" colspan="1" valign="top">Describes a simple vertical bounding box. For a more detailed geospatial coverage, see the [http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#suggested_geospatial suggested geospatial attributes].</td>
 
                <td valign="top">metadata/geospatialCoverage/updown/start</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:verticalElement/gmd:EX_VerticalExtent/gmd:minimumValue/gco:Real</td>
 
                <td></td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#geospatial_vertical_max_Attribute geospatial_vertical_max]</td>
 
                <td valign="top">metadata/geospatialCoverage/updown/size</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:verticalElement/gmd:EX_VerticalExtent/gmd:maximumValue/gco:Real</td>
 
                <td></td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#time_coverage_start_Attribute time_coverage_start]</td>
 
                <td rowspan="4" colspan="1" valign="top">Describes the temporal coverage of the data as a time range.</td>
 
                <td valign="top">metadata/timeCoverage/start</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:temporalElement/gmd:EX_TemporalExtent/gmd:extent/gml:TimePeriod/gml:beginPosition</td>
 
                <td></td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#time_coverage_end_Attribute time_coverage_end]</td>
 
                <td valign="top">metadata/timeCoverage/end</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:temporalElement/gmd:EX_TemporalExtent/gmd:extent/gml:TimePeriod/gml:endPosition</td>
 
                <td></td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#time_coverage_duration_Attribute time_coverage_duration]</td>
 
                <td valign="top">metadata/timeCoverage/duration</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:extent/gmd:EX_Extent/gmd:temporalElement/gmd:EX_TemporalExtent/gmd:extent/gml:TimePeriod/gml:beginPosition provides an ISO8601 compliant description of the time period covered by the dataset. This standard supports descriptions of [http://en.wikipedia.org/wiki/ISO_8601#Durations durations].</td>
 
                <td></td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#time_coverage_resolution_Attribute time_coverage_resolution]</td>
 
                <td valign="top">metadata/timeCoverage/resolution</td>
 
                <td></td>
 
                <td></td>
 
                <td>Extent</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#standard_name_vocabulary_Attribute standard_name_vocabulary] </td>
 
                <td valign="top">The name of the controlled vocabulary from which variable standard names are taken. </td>
 
                <td valign="top">metadata/variables@vocabulary</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:thesaurusName/gmd:CI_Citation/gmd:title/gco:CharacterString </td>
 
                <td></td>
 
                <td>Text Search</td>
 
            </tr>
 
            <tr>
 
                <td valign="top">[http://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/formats/DataDiscoveryAttConvention.html#license_Attribute license]</td>
 
                <td valign="top">Describe the restrictions to data access and distribution. </td>
 
                <td valign="top">metadata/documentation[@type="rights"]</td>
 
                <td valign="top">/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:resourceConstraints/gmd:MD_LegalConstraints/gmd:useLimitation/gco:CharacterString</td>
 
                <td></td>
 
                <td></td>
 
            </tr>
 
        </table>
 
  
 
=Suggested=
 
=Suggested=

Revision as of 14:45, September 2, 2014

       DRAFT - Not ready for use

Version and Status

This version is designated as Version 2.0 This page always has the current version of the Attribute Convention for Data Discovery (ACDD). As it is updated, the version number at the top of the page will be updated.

See the [category page] for information on the history of this convention.

Development

Any development version of the ACDD definitions is maintained at Attribute_Convention_for_Data_Discovery_(ACDD)_Working.

Overview

The NetCDF Group at Unidata has recommended attributes for data discovery . The Attribute Convention for Data Discovery (ACDD) addresses that need, providing definitions for NetCDF global attributes that will help data to be located efficiently.

Alignment with NetCDF and CF Conventions

The NetCDF User Guide (NUG) provides basic recommendations for creating NetCDF files; the NetCDF Climate and Forecast Metadata Conventions (CF) provides more specific guidance. The ACDD builds upon and is compatible with these conventions; it may refine the definition of some terms in those conventions, but does not preclude the use of any attributes defined by the NUG or CF.

The NUG does not require any global attributes, though it recommends and defines two, title and history; CF specifies many more. ACDD 1.2 adopts all CF 1.6 global attributes with the exception of 'institution'; we specify 'creator_institution' and 'publisher_institution', to provide more provenance information. We also modify the syntax of the 'Conventions' attribute; we adopt the NUG recommendation to supply all conventions in a single attribute. This change has been approved by the CF Conventions Committee and will be part of CF 1.7, which is not yet published.

Attribute Crosswalks

Many of these attributes correspond to general discovery metadata content, so they are available in many metadata standards. This Unidata crosswalk to THREDDS page includes also includes a crosswalk to ISO 19115-2. Note that the attribute names link to the Unidata definitions. Many of these elements are included in the ISO 19115 Core specification. They are indicated in this Table by an M, O, or C in parentheses. An “M” indicates that the element is mandatory. An “O” indicates that the element is optional. A “C” indicates that the element is mandatory under certain conditions.

Additional Metadata: metadata_link attribute

Other metadata dialects (i.e. ISO 19115) can provide information about collections and more details about the dataset. If additional metadata exists, you can make users aware of it by adding a global attribute named "metadata_link" to the netCDF file. The value of this attribute is a URL that gives the location of the more complete metadata.


Maintenance of Metadata

ACDD attributes, like all NetCDF attributes, characterize their containing (parent) granules. As NetCDF data are processed (e.g., through subsetting or other algorithms), these characteristics can be altered. The software or user processor is responsible to update these attributes as part of the processing, but some software processes and user practices leave them unchanged. This affects both consumers and producers of these files, which comprises three roles:

  • developers of software tools that process NetCDF files;
  • users that create new NetCDF files from existing ones; and
  • end users of NetCDF files.

NetCDF file creators (the first two roles) should ensure that the attributes of output files accurately represent those files, and specifically should not "pass through" any source attribute in unaltered form, unless it is known to remain accurate. NetCDF file users (all three roles) should verify critical attribute values, and understand how the source data and metadata were generated, to be confident the source metadata is current.

The ACDD geospatiotemporal attributes present a special case, as this information is already fully defined by the CF coordinate variables (the redundant attributes are recommended to simplify access). Errors in these attributes will create an inconsistency between the metadata and data of the granule or file. The risk of these 'inconsistency errors' is highest for files that are aggregated into longer or larger products, or subset into shorter or smaller products, such as files from numerical forecast models and gridded satellite observations. For this reason, some providers of those data types may choose to omit the ACDD geospatiotemporal attributes from their files. If the ACDD geospatiotemporal attributes are present, checking them against the CF coordinate variables can serve as a partial test of the metadata's validity.


Metadata Link

The netCDF metadata model is focused on providing "use metadata" for the data included in the file (or granule). Other metadata dialects (i.e. ISO 19115) can provide information about collections and more details about the dataset. In order to make users aware of that additional metadata we recommend adding a global attribute named "Metadata_Link" to the netCDF file. The value of this attribute is a URL that gives the location of the more complete metadata. This element is not included in the current version of the NetCDF Attribute Convention for Dataset Discovery.

Global Attributes

Highly Recommended

Attribute Description THREDDS ISO 19115-2 OGC CSW Rubric Category
title
A short phrase or sentence describing the dataset; this is a NetCDF Users Guide (NUG) attribute. dataset@name
/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:title/gco:CharacterString (M)
Title Text Search
summary
A paragraph describing the dataset, analogous to an abstract for a paper. metadata/documentation[@type="summary"]
/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:abstract/gco:CharacterString (M)
Abstract Text Search
keywords
A comma-separated list of key words and/or phrases. Keywords may be common words or phrases, terms from a controlled vocabulary (GCMD is often used), or URIs for terms from a controlled vocabulary (see also keywords_vocabulary attribute). metadata/keyword
/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gco:CharacterString
Subject Text Search
Conventions A list of the conventions followed by the dataset; blank space separated is recommended but commas should be used if any convention name contains blanks. For files that comply with this version of ACDD, include the term ACDD-1.2. This attribute is defined in NUG.

Recommended